Prince William celebrates his 30th birthday today, triggering a £10 million ($15.7 million) inheritance from his late mother Diana.

The late Princess of Wales left the bulk of her estate to sons William and Harry, who were aged 15 and 12 at the time of her death in a Paris car crash in 1997. The figure has also risen over time, through investments. The boys get an equal share of the estate. But the executors of her will decided that the inheritances should not be handed over to William and Harry until each turned 30.

There has been speculation that William and wife Catherine – the Duke and Duchess of Cambridge – may use the money to buy a country house, but that now seems less likely as William is expected to sign up for another tour with the Royal Air Force’s Search and Rescue team. That would involve him moving to another base, away from Anglesey, where the couple currently live for most of the year.

William and Catherine, who married last year, are expected to celebrate Prince William’s 30th birthday with friends before returning to their rented farmhouse on Anglesey, an island off the north west coast of Wales.